This paper presents a methodology for performing architecture definition and assessment prior to, or during, program formulation that utilizes a centralized, integrated architecture modeling framework operated by a small, core team of general space architects. This framework, known as the Exploration Architecture Model for IN-space and Earth-toorbit (EXAMINE), enables: 1) a significantly larger fraction of an architecture trade space to be assessed in a given study timeframe; and 2) the complex element-to-element and element-to-system relationships to be quantitatively explored earlier in the design process. Discussion of the methodology advantages and disadvantages with respect to the distributed study team approach typically used within NASA to perform architecture studies is presented along with an overview of EXAMINE's functional components and tools. An example Mars transportation system architecture model is used to demonstrate EXAMINE's capabilities in this paper. However, the framework is generally applicable for exploration architecture modeling with destinations to any celestial body in the solar system.

This paper presents an analysis of the impact of ISRU, reusability, and automation on sustaining a human presence on Mars, requiring a transition from Earth dependence to Earth independence. The study analyzes the surface and transportation architectures and compared campaigns that revealed the importance of ISRU and reusability. A reusable Mars lander, Hercules, eliminates the need to deliver a new descent and ascent stage with each cargo and crew delivery to Mars, reducing the mass delivered from Earth. As part of an evolvable transportation architecture, this investment is key to enabling continuous human presence on Mars. The extensive use of ISRU reduces the logistics supply chain from Earth in order to support population growth at Mars. Reliable and autonomous systems, in conjunction with robotics, are required to enable ISRU architectures as systems must operate and maintain themselves while the crew is not present. A comparison of Mars campaigns is presented to show the impact of adding these investments and their ability to contribute to sustaining a human presence on Mars. In order to achieve the Earth independence that is required in pioneering, the study team adopted the motto, "Don't Manage Scarcity; Exploit Abundance." In-Situ Resource Utilization (ISRU) involves extracting and utilizing local resources so that they do not need to be delivered from Earth. ISRU is a critical capability for Earth independence, and Mars has several resources in its atmosphere, surface, and even gravitational influence that can be exploited. The atmosphere can be used to reduce the energy of an entering vehicle. Aerocapture and aeroentry use the atmosphere to decelerate a vehicle without using propellant that would nominally be delivered from Earth, reducing the propellant requirements. Gravity assists, which can be considered gravitational ISRU, at the Moon or Mars also reduce the propellant requirements. Also, the 95 percent carbon dioxide and three percent nitrogen content of the Martian atmosphere can be acquired and utilized to produce useful materials and gases. 2 Water is in the regolith and subsurface of Mars, which permits the production of propellant (methane, hydrogen, other hydrocarbons, and oxygen) and crew consumables (water, oxygen, nitrogen, and food). When combined with

The National Aeronautics and Space Administration (NASA) is currently developing options for an Evolvable Mars Campaign (EMC) that expands human presence from Low Earth Orbit (LEO) into the solar system and to the surface of Mars. The Hybrid in-space transportation architecture is one option being investigated within the EMC. The architecture enables return of the entire in-space propulsion stage and habitat to cis-lunar space after a round trip to Mars. This concept of operations opens the door for a fully reusable Mars transportation system from cis-lunar space to a Mars parking orbit and back.This paper explores the reuse of in-space transportation systems, with a focus on the propulsion systems. It begins by examining why reusability should be pursued and defines reusability in space-flight context. A range of functions and enablers associated with preparing a system for reuse are identified and a vision for reusability is proposed that can be advanced and implemented as new capabilities are developed. Following this, past reusable spacecraft and servicing capabilities, as well as those currently in development are discussed. Using the Hybrid transportation architecture as an example, an assessment of the degree of reusability that can be incorporated into the architecture with current capabilities is provided and areas for development are identified that will enable greater levels of reuse in the future. Implications and implementation challenges specific to the architecture are also presented.

The objective of the HIAD Mission Applications Study is to quantify the benefits of HIAD infusion to the concept of operations of high priority exploration missions. Results of the study will identify the range of mission concepts ideally suited to HIADs and provide mission-pull to associated technology development programs while further advancing operational concepts associated with HIAD technology. A summary of Year 1 modeling and analysis results is presented covering missions focusing on Earth and Mars-based applications. Recommended HIAD scales are presented for near term and future mission opportunities and the associated environments (heating and structural loads) are described.

This paper presents a new conceptual launch vehicle design in the Bantam-X payload class. The new design is called Stargazer. Stargazer is a two-stage-toorbit (TSTO) vehicle with a reusable flyback booster and an expendable LOX/RP upper stage. Its payload is 300 lbs. to low earth orbit. The Hankey wedge-shaped booster is powered by four LOX/LH2 ejector scramjet rocket-based combined-cycle engines. Advanced technologies are also used in the booster structures, thermal protection system, and other subsystems. Details of the concept design are given including external and internal configuration, mass properties, engine performance, trajectory analysis, aeroheating results, and a concept cost assessment. The final design was determined to have a gross mass of 115,450 lb. with a booster length of 99 ft. Recurring price per flight was estimated to be $3.49M. The overall conceptual design process and the individual tools and processes used for each discipline are outlined. A summary of trade study results is also given. NOMENCLATURE C t thrust coefficient I sp specific impulse (sec.) q dynamic pressure (psf) T/W e engine thrust-to-weight ratio This paper summarizes part of an 18 month Bantam-X concept study conducted by the Space Systems Design Laboratory at Georgia Tech with the support and collaboration of NASA Marshall Space Flight Center. The study goal was to investigate a promising concept based on rocket-based combinedcycle (RBCC) propulsion for longer range Bantam-class missions. NASA MSFC currently has an ongoing development program in RBCC engines.